We will examine the relative contributions of maternal mRNA and synthesis and turnover of newly synthesized mRNA in the expression of the histone genes in cleaving sea urchings, and also examine the role of non-histone proteins in early development. The amount of various kinds of histone mRNA present in early sea urchin embryos will be determined by using radioactive single stranded DNA probes prepared from cloned sea urchin histone genes. DNA excess titrations will provide information on the amount and subcellular localization of the various mRNA's. The contributions of new synthesis to the total RNA will be evaluated by radioactive and density labeling methods. The rate of transcription will be determined and compared to the rate of appearance of mRNA in the cytoplasm. Turnover rates of histone mRNA will be calculated, and also directly determined in chase experiments. The stability of "early" and "late" forms of histone mRNA will be compared. Subcellular location of histone mRNA will be determined by DNA titrations of various fractions. The effects of cell division and DNA synthesis on the increase in histone mRNA synthesis at the 4th cell division will be examined. Experiments on the number and kinds of non-histone proteins present in chromatin will be carried out by application of 2D gel techniques to chromatin from different stages and different cell types, using both sea urchins and X. laevis embryos. A double labeling technique that distinguishes proteins made during oogenesis from those made during embryogenesis will be applied. We hope to identify proteins of the egg that later become associated with blastomere chromatin and that may be involved in determination.